Liar corresponds approximately to the cos 4 * law. The Steinheil objective is clearly 
better. In the development of the Russar (Figure 8) and Aviogon (Figure 5) objectives, 
an intentional effort was made to improve the illumination over the cos 4 a law. The 
aim of Mr. Russinov was to produce a distortion free super wide angle lens with 
tolerable illumination loss 7 . 
Fig. 8 Section through the super wide angle objective “ Russar” by Russincv. 
On the other hand, L. Bertele developed in 1946 a fundamental type of large aperture 
wide angle objective for 90° coverage with minimum distortion and maximum picture 
quality. Since only pictures with good marginal illumination are suitable for precise 
photogrammetric work, special attention had to be given to this problem 8 . 
Fig. 9 An oblique view of the diaphragm of an old wide angle objective. The diaphragm plane 
appears to turn away from the observer. Less light passes through than with a front diaphragm. 
7 M. Russinov. Objectif photographique anastigmate orthoscopique à angle élargi. 
French patent description No. 935617/1948. 
8 L. Bertele. Ein neues Weitwinkelobjektiv für die Luftbildmessung. Photogrammetria 1951/52.